This invention relates to a frame assembly and more particularly to the hitch assembly on the front frame of a construction machine.
In the operation of construction machines, it has been found desirable to steer the machine by rotating the front portion of the machine with respect to the rear portion. In order to do this, it is necessary to provide two separate frames that are pinned together about a vertical axis and extend hydraulic cylinders therebetween to obtain the desired rotation or articulation. Typically, the engine and drive train components are mounted on the rear portion of the machine and the work implement is mounted on the front portion of the machine.
In the case of some machines, the articulated wheel loader, for example, the front frame portion is subject to extremely high loads from several different sources. One primary source occurs during operation of the work implement. The work implement is typically attached to the front frame by a pair of lift arms each of which are raised and lowered by a pair of lift cylinders that extend between each lift arm and the front frame. The weight of the lift arms and loaded work implement are the source of substantially loading and it is necessary to provide a front frame assembly with sufficient width to accommodate such loading.
Yet another source of loading occurs during the steering function of the vehicle. Since the front axle is mounted to the front frame, there must be substantial support for it as it steered over all kinds of terrain. The forces applied by the steering cylinder to rotate the front frame with respect to the rear frame to steer the axle are also quite large. The support brackets for the steering cylinders are normally positioned on the sides of the front frame assembly at locations that are spaced from the axle centerline, through which the forces are transferred. As this spacing increases, so to do the forces passing therethrough, which ultimately requires exceptionally large support brackets for mounting structures.
A great deal of these forces are transmitted from the front frame to the rear frame through the hitch components. For that reason, the area around each of the hitch brackets, especially on the front frame, are normally reinforced by a plurality of support plates. Typically these support plates are isolated around each of the individual hitch plates and numerous plates are required to provide adequate support.
All these factors inherently result in a structure that is quite large in both height and width. With the increase in size however, come several disadvantages. The overall complexity and weight are exceptionally costly in terms of the numbers of components that must be welded together and the expense of material. Additionally, the operation of the machine is hampered because the large size of the structure can reduce the operators visibility to the work implement. This especially true with respect to the line of sight to the base and the corners of the implement.
The present invention is directed to overcoming one or more of the problems set forth above.
In one aspect of the present invention, a hitch assembly is provided for the front frame assembly of an articulated machine that includes a pair of side plates that have first and second end portions and are positioned in spaced, parallel relation to one another. Upper and lower hitch plates are positioned between and secured to the side plates at the second end portions thereof with the lower hitch plate being vertically spaced from the upper hitch plate. A first support plate having an upper end portion secured to the upper hitch plate and a lower end portion secured to the lower hitch plate is positioned between and is secured to each of the side plates along the entire lengths of the opposing sides of the support plate.
With a hitch assembly as set forth above, support for the loads that are directed through the hitch assembly during operation of the machine are accommodated by a structure that utilizes a minimum of structural components thus reducing the complexity and cost of the overall structure as well the manufacturing and assembly processes.